As the speed at which a motor vehicle travels increases, because of differences in airspeed and pressure generated underneath the vehicle chassis relative to the top of the vehicle, lift is generated and the nose of the vehicle raises slightly. This can affect handling and stability, particularly for vehicles being operated at higher speeds. This effect on handling and stability cam be exacerbated in front-wheel drive vehicles. To address this problem it is known to provide aerodynamic front air dams for motor vehicles, to assist in managing airflow. By use of front air dams, motor vehicle fuel efficiency and passenger cabin acoustics can be improved Likewise, front air dams assist in limiting motor vehicle front end lift by creating a down-force, forcing the vehicle nose down and so improving vehicle handling and stability. Still more, properly designed front air dams may assist in engine cooling and therefore efficiency.
Of necessity, a front air dam extending below the motor vehicle bumper and chassis reduces ground clearance. This may be of little import when the vehicle is traveling on a smooth road. However, on a rough road or in the event of encountering an obstacle on the road, any reduction in ground clearance may result in vehicle damage and potentially a loss of stability and handling. Even if the vehicle does not actually strike an obstacle in the road, sudden braking or steering may cause the vehicle nose to dip or roll, in turn causing a portion of the front air dam to strike the road surface and cause damage and potential impairment of vehicle stability and handling.
For this reason, it is known in the art to provide retractable front air dams. Such retractable air dams, while effective for their intended purpose, suffer from a flaw. Typically, even in vehicles equipped with forward sensors for detecting obstacles, particularly if the vehicle is traveling at higher speeds, when a road obstacle is encountered only a very limited time to react by braking or steering is available. Likewise, in the event of sudden braking or steering sufficient to cause the vehicle nose to dip or roll, only a very limited time to retract the air dam is available. That limited time may not be sufficient to retract the air dam quickly enough to avoid contact with an obstacle or with the road surface as described above.
To solve this and other problems, the present disclosure relates to a compact and efficient system for lowering and raising a motor vehicle front air dam. The described system also allows raising and lowering the front air dam to a position determined to provide the most efficient height/road clearance in terms of best fuel economy and/or underbody component cooling, but also provides a retraction system allowing rapid retraction of the air dam on detection of a road obstacle or rough road, or on application of heavy braking or steering likely to cause the air dam to contact the road surface.